1. Field of the Invention
This invention relates generally to an apparatus for promoting the uniform distribution of air in a diffuser and evaporator of an air conditioning system. More particularly the invention pertains to the shape, orientation and location of diffuser guide vanes.
2. Description of the Prior Art
The blower/scroll in an automotive heating ventilation and air conditioning (HVAC) system produces high speed, non-uniform flow that tends to produce high flows on the outer periphery due to centrifugal forces. Generally the cross sectional area of the scroll outlet is small (compared to that of the evaporator inlet), the air velocity at the scroll outlet is high (about 25 m/sec.), and the flow is directed in an arcuate path as it leaves the scroll. These factors cause a flow speed gradient, in which air speed is greatest near the outer wall of the scroll and lowest near its inner wall.
Uniform velocity distribution at a diffuser outlet and in the evaporator is important to ensure efficient evaporator performance, higher air flow, and possible reduced noise generation as the air passes through the evaporator core.
A variable blower control (VBC) module, an electronic controller located in the diffuser downstream of the scroll and a few inches upstream of the evaporator, requires high air speed across its surfaces in order to maintain the VBC adequately at a cool temperature. The VBC module's heat load is about 70 watts when the blower is operating. Furthermore, the presence of the VBC module in the diffuser may have an adverse effect on uniform air speed within the diffuser and evaporator.
A need exists in the industry for an air diffuser that produces uniform velocity distribution of air entering an evaporator, a high rate of air flow, a reduction in noise generation as the air passes through the evaporator core, and that is able to meet or exceed minimum evaporator coverage specifications.